Generator cooling



m s f Ry 5 1 W M H 6 T mum N 00 E M m WA H I. I A m m E R Y m B 2 Jan. 20, 1953 R. A. BAUDRY ETAL GENERATOR COOLING Flled Aprll 18. 1952 Fig. I.

WITNESSES: wc

J 3 R. A. BAUDRY ETAL 2,626,365

GENERATOR COOLING Filed April 18. 1952 2 SHEETSSHEET 2 WITNESSES:

I INVENTORS Rene A. Boudry and W :7 Y Paul R. Heller.

ATTORNEY Patented Jan. 20, 1953 GENERATOR CO OLING Ren A. Baudry, Pittsburgh, and Paul R. Heller, Irwin, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., 2. corporationof Pennsylvania Application April18, 1952-, Serial No; 282',982

2 Claima Our invention relates to cooling of dynamothrough the cooling-ducts of the rotor, this increased fan-pressure being obtained by the use of. booster-fans for creating an additional fanpressurewhich is effective only for, the rotorcooling and not for the stator-cooling,

There are time, however, when the stator cooling-system can advantageously use the same high fan-pressure as the rotor-cooling system, or when it is undesirable to use a separate booster-fan for applying a higher differential pressure to the rotor than to the stator of the machine. Our, present inventionrelates to such a situation, in which it is necessary to do two things in order tov provide the necessary pressure-differential for forcing the recirculating gas through the rotormember. This is particularly true when the rotor-coolingsystem is one in which the coolingducts, which coo-l the rotor-conductors, are vented to the air gap at the center of the'machine, midway between the ends of the rotor-core. In order to provide an adequate differential pressure between the pressurized end-zone and the air gap, so as to produce the necessary rotor-cooling, we provide an annular air-gap baflie, for providing a restricted gas-passage from the pressurized endzone into the air gap, and we provide restricted passages in the stator-ventilating path from thepressurized end-zone across the outside of the stator-core to an intake-chamber and thenceradially inwardly through radial ventilating-spaces in the stator core, to the air gap, so as to make sure that there is the necessary pressure-differential between the pressurized end-Zone, and the air gap, to properly cool the rotor, member.

A simplified illustrative form of embodiment of our invention is shown in the accompanying drawing, wherein;

Figure 1 is a partially diagramamtic and much simplified longitudinal sectional view, not to scale, illustrating an exemplary form of embodiment of ourinvention as applied to. atwo-pole turbine generator, thesection-plane through the genera 2 ator being indicated by the broken section-line II in Fig. 2; and

Fig. 2 is a transverse cross-sectional view, on the section-plane II--II in Fig. l.

The drawing illustrates, the application of our invention to a large turbine generator, which may be exemplified by a two-pole, -cycle, three.- phase generator having a rating in excess of 150,000 kilowatts, at a. voltage of at least 5,000 or 10,000 volts, usualy more, although we are not limited, of course, to any particular rating. The generator comprisesv a stator member 3 and a rotor member 4, having an air gap 5 therebetween. These stator and rotor members. 3 and 4 are enclosed in a substantially gas-tight housing 6 which is filled with gas, preferably withhydrogen, at any suitable pressure, said hydrogen bathing both the stator member 3 and the rotor member 4, as is well. known.

The stator, member 3 is provided with an annular laminated stator-core 1', having windingreceiving stator-slots 8. The stator-core 1 comprises a plurality of bundles or" stator-laminations separated by radial ventilating-spaces 9 and ID. A stator-winding II is provided, having coil-sides lying within the stator-slots 8 and also having end-windings I2.

Each end of the rotor member carries a fan" or blower" I3 which creates a sufficiently large pressure-difierential to cause the proper circulation of the hydrogen. Each fan 13 is associated with a suitable shroud or partition-means M for producing a pressurized end-zone 5; at that end ofthe machine, for maintaining the necessary differential gas-pressure for recirculating the gas. The hydrogen-circulation system also includes one or more coolers it, which may be of a conventional type and disposition.

Therotor member 4 includes a cylindrical rotor-core I! which has a plurality of windingreceiving rotor-slots l8. A rotor-winding I9 is provided; having cooling-ducts 20 and coil-sides 2|- lying within the rotor-slots G8. The rotorwinding I9-also has end-windings 22. The cooling-ducts 20 for the rotor-winding might be any sort of hydrogen-flow ducts for directly cooling the rotor-winding conductors, and especially the coil-sides 2| which lie within the rotor-slots I0. The cooling-ducts 20 for the rotor-winding iii are preferably formed by means of hollow rotorconductors 23, as shown, in which case these cooling-ducts extend in cooling-relation to the rotor end-windings 22 as well as to the rotor coil-sides 2|. The rotorend-windings 22 are surrounded by-a retaining; ring 24, in a known manner.

The rotor member has a gas-inlet space 25 under the retaining ring 24, preferably at each end of the machine, whereby gas may enter the rotor member from the pressurized end-zone I at that end of the machine. From this gas-inlet space 25, the cooling-gas is lead into the rotorconductor cooling-ducts 20, by any suitable communication-means such as holes 26. At some point, preferably near the middle of the rotorcore IT, at any rate intermediately between the ends of the rotor-core, we provide gas-outlet means 21, in a known manner, for discharging the cooling-gas from the rotor cooling-ducts into the air gap 5.

In the stator member 3, the stator end-windings I2 are supported, in a known manner, by an annular end-winding support 28, which lies within or under the end-windings I2, adjacent to the pressurized end-zone I5 at each of the respective ends of the machine. In accordance with our present invention, each end-winding support 28 has an annular baflie-portion 29 which approaches close to the retaining ring 24 at that end of the machine, for providing a restricted gas-passage therebetween, so that there can be a substantial pressure-differential between the pressurized end-zone I5 and the air gap 5.

Around the outer periphery of the stator-core I, between said core and the housing 6, we provide any known or desired form of zoning-means, such as a plurality of axially spaced partition-means BI, surrounding said stator-core, for providing a plurality of discharge-zones 32, at least includin one discharge-zone 32 at each end of the statorcore I, Axially displaced or interspersed with respect to the discharge-zones 32, the partitionmeans 3i also produce at least one intermediately disposed intake-zone 33, surrounding the statorcore I. As is well understood, in this type of machine, communication-passages are provided from the discharge-zones 32 to the cooler I6, and through the cooler to the fan-and-partition assembly I4-I 5 for returning the recirculating gas to the pressurized end-zones I5. We also provide a communication-means, such as a pipe 34, for conducting gas from each of the pressurized endzones 5 to the intake-zone 33, or to the nearest intake-zone 33, if ther are more than one such zone, which is also, or may be, in accordance with known practice.

In operation, the rotor member 4 is cooled by means of high-velocity gas, which flows from each of the pressurized end-Zones I5, through the gasinlet space under the retaining ring 24 at that end of the rotor member, and thence through the holes 26 into the rotor-ducts 20, and thence to the gas-outlet means 21 at the center of the rotor, where the gas is discharged into the air gap 5. From the air gap 5, a relatively low-pressuredrop communication path, or gas-flow path, is provided through the gas-discharging radial ventilating-spaces 9 into the discharge-zones 32, and thence through the cooler I6 and back to the fan I3, without much gas-pressur difierential existing between the air gap 5 and the intake side of the fan I3.

At the same time, the stator member 3 must be cooled by some suitable cooling-means. It is contemplated, within the scope of our present invention, that any suitable stator-cooling means may be used, whether or not it includes the direct cooling of the stator-winding II, as set forth in our application Serial No. 248,852. At any rate, in the combination to which our present inventor-core I.

4 tion is particularly applicable, the stator-cooling means includes at least the radial ventilatingspaces 9 and Ill in the stator-core. The gas which discharges from the air gap 5 through the discharging radial ventilating-spaces 9 cools the stator-core, at the portions of the core which are surrounded by the discharge-zones 32. The central or intermediate portion or portions of the stator-core I, which are surrounded by the intake-zone or zones 33, are cooled by gas which flows inwardly to the air gap, through the intaking radial ventilating-spaces ID in the statorcore, this in-fiowing gas being supplied from the pressurized end-zones I5 through the pipes 34 to the intake-zone or zones 33 which surround the intaking ventilating-space or spaces I I] of the stator-core.

In accordance with our present invention, we provide means for maintaining the necessary pressure-difierential between the air gap 5 and a single pressurized end-zone I5 at each end of the machine. To this end, it is necessary, not only to provide the air-gap baffle 29, but also to provide some form of gas-passage restriction, in the path of the in-flowing stator-cooling gas which flows through the pipes 33 to intake-zone or zones 33, and thence through the intaking radial ventilating-space or spaces Ill of the sta- In th broadest sense of our invention, this pressure-conforming restriction may take place anywhere within the path which has just been mentioned for the in-flowing statorcooling gas. However, we preferably reduce the number, or the size, or both, of the intaking radial ventilating-spaces It, so that the aggregate cross-sectional area of the intake radial ventilating-space or spaces it shall be consider-- ably less than the aggregate cross-sectional area of the discharging ventilating-spaces 9. Hence the intaking radial ventilating-spaceor spaces I0 provide a relatively high-pressure-drop communication-means between the intake-zone 33 and the air ap 5, while the discharging radial ventilating-spaces 9 provide a relatively low-pressure-drop communicatiommeans from said air gap 5 to the discharge zones 32.

V In this way, it will be seen that we provide a relatively large prBssure-difierential between each pressurized end-zone and the air gap 9, for forcing the recirculating gas at an adequately high velocity through the rotor member 5 so as to obtain adequate rotor-cooling without having to use a booster-fan for obtaining a special high-pressure end-zone for securing the necessary rotorcooling gas-velocities.

While we have illustrated our invention, very diagrammatically, in a much simplified form, in only one illustrative form of embodiment, we wish it to be understood that our invention is not limited to the precise details which are shown or described.

We claim as our invention:

1. A dynamo-electric machine comprising a stator member and a rotor member having an air gap therebetween, a substantially gas-tight housing enclosin said stator and rotor members, a filling of a gas bathing both said stator member and said rotor member within said housing, and a recirculation-means for said gas; (a) said recirculation-means including a cooler therein, and also including a fan-and-partition means for producing a pressurized end-zone at one end of the machine for maintaining a differential gas-pressure for recirculating the gas; (12) said rotor mem'- ber including a cylindrical rotor-core having winding-receiving rotor-slots, a rotor-winding having a cooling-duct means and coil-sides lying within said rotor-slots, said rotor-winding also having end-windings, said rotor member including a retaining ring surrounding said end-windings of the rotoi winding, said rotor member also having gas-inlet means under said retaining ring whereby gas may enter the rotor member from said pressurized end-zone, means for providing a communication from said gas-inlet means to said cooling-duct means, and a gas-outlet means discharging into said air gap intermediately between the ends of the rotor-core; and (c) said stator member including a laminated stator-core having winding-receiving stator-slots, said statorcore comprising a plurality of bundles of statorlaminations separated by radial ventilatingspaces, a stator-winding having coil-sides lying within said stator-slots, and also having endwindings, said stator member also having an annular end-winding support lying within the endwindings of said stator-winding adjacent to said pressurized end-zone, said end-winding support having an annular baffle-portion approaching close to said retaining ring for providing a restricted gas-passage therebetween, said stator member also having a plurality of axially spaced partition-means surrounding said stator-core for providing a plurality of discharge-zones and at least one intermediately disposed, axially displaced intake-zone surrounding said stator-core, communication-means from said discharge-zones to said cooler and through said cooler to said fanand-partition means for said pressurized endzone, for recirculating the gas, and communication-means from said pressurized end-zone to said intake-zone, characterized by such relative sizes of the communication-passages of said stator member that there is a relatively small pressure-drop from said air-gap through the radial ventilatingspaces which communicate with said dischargezones and thence through said cooler to said fanand-partition means, While there is a relatively large pressure-drop from said pressurized endzone to said intake-zone and thence, through the radial ventilating-space or spaces which communicate with said intake-zone, back to said air gap, whereby to provide a relatively large pressure-differential between the pressurized endzone and the air gap for forcing the recirculating gas through said rotor member.

2. A dynamo-electric machine comprising a stator member and a rotor member having an air gap therebetween, a substantially gas-tight housing enclosing said stator and rotor members, a filling of a gas bathing both said stator member and said rotor member within said housing, and a recirculation-means for said gas; (a) said recirculation-means including a cooler therein, and also including a fan-and-partition means for producing a pressurized end-zone at one end of the machine for maintaining a differential gas-pressure for recirculating the gas; (2)) said rotor member including a cylindrical rotor-core having winding-receiving rotor-slots, a rotor-winding having a cooling-duct means and coil-sides lying within said rotor-slots, said rotor-winding also having end-windings, said rotor member including a retaining ring surrounding said end-windings of the rotor-winding, said rotor member also having gas-inlet means under said retaining ring whereby gas may enter the rotor member from said pressurized end-zone, means for providing a communication from said gas-inlet means to said cooling-duct means, and a gas-outlet means discharging into said air gap intermediately between the ends of the rotor-core; and (c) said stator member including a laminated stator-core having winding-receiving stator-slots, said stator-core comprising a plurality of bundles of stator-laminations separated by radial ventilating-spaces, a stator-winding having coil-sides lying within said stator-slots, and also having end-windings, said stator member also having an annular end-winding support lying within the end-windings of said stator-winding adjacent to said pressurized end-zone, said end-winding support having an annular bathe-portion approaching close to said retaining ring for providing a restricted gas-passage therebetween, said stator member also having a plurality of axially spaced partition-means surrounding said stator-core for providing a plurality of discharge-zones and at least one intermediately disposed. axially displaced intake-zone surrounding said stator-core, relatively low-pressure-drop communication-means from said discharge-zones to said cooler and through said cooler to said fan-and-partition means for said pressurized end-zone, for recirculating the gas, and relatively low-pressure-drop communication-means from said pressurized end-zone to said intake-zone, characterized by the aggregate cross-sectional area of the discharging radial ventilating-spaces which communicate with said discharge-zones being considerably larger than the aggregate cross-sectional area of the intaking radial ventilating-space or spaces which communicate with said intakezone, so that said discharging radial ventilatingspaces provide a relatively low-pressure-drop communication-means from said air gap to said discharge-zones, while said intaking radial ventilating-space or spaces provide a relatively high-pressure-drop communication-means between said intake-zone and said air gap, whereby to provide a relatively large pressure-differential between the pressurized end-zone and the air gap for forcing the recirculating gas through said rotor member.

RENE A. BAUDRY. PAUL R. HELLER.

.No references cited. 

